1. Field of the Invention
The present invention concerns a device for increasing the dynamic range of a camera so that it is tolerant of large differences in brightness between the points of the scene of which an image is viewed.
2. Discussion of the Background
Its applications are mainly in shooting under uncontrolled light conditions outdoors, in endoscopy and in welding robots.
Known tube or CCD type cameras are very intolerant of smearing and blooming and have a very low dynamic range (ratio of brightest to least bright areas viewed correctly and simultaneously) in the order of 100.
They are also insufficiently sensitive for shooting at night.
Other devices have an image sensor and one or more passive screens disposed optically in front of the image sensor and controlled by it which have a greater dynamic range but provide a highly unstable image. They provide closed loop matrix optical control and suffer from either oscillation of the output signal and the image transmitted or a response time very much greater than that of the image sensor.